Solar Terrestrial Activity Report

Last major update issued on June 11, 2005 at 04:35 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 4, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 4, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 4, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update June 4, 2005)]

Recent activity

The geomagnetic field was very quiet to quiet on June 10. Solar wind speed ranged between 308 and 353 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 114.7. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6).
Three hour interval K indices: 21111112 (planetary), 11111211 (Boulder).

The background x-ray flux is at the class B1-B2 level.

At midnight there were 5 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 1 C class event was recorded during the day.

Region 10772 rotated to the southwest limb. Flare: C2.0 at 03:10 UTC.
Region 10773 decayed slowly and lost the leader spot.
Region 10775 decayed and became less complex with no magnetic delta structures remaining.
Region 10776 did not change significantly and remains capable of producing an M class flare.
New region 10777 emerged near the northeast limb on June 9 and was numbered by SEC the next day.

Coronal mass ejections (CMEs)

June 9-10: No obvious fully or partly Earth directed CMEs were observed in LASCO images.
June 8: At least a partial halo CME was observed in LASCO C3 images during the late afternoon and early evening. The ejected material was first observed over the southwest limb and was likely related to a filament eruption to the north of region 10772.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

No obvious coronal holes are currently near Earth facing positions.

Processed SOHO/EIT 284 image at 01:06 UTC on June 6. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled most of  June 11. The CME observed on June 8 could reach Earth late on June 11 or early on June 12 and cause unsettled to active conditions. Quiet to unsettled is likely on June 13-14.

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)
Coronal hole indicator CME indicator M and X class flare indicator

1) Effects from a coronal hole could reach Earth within the next 5 days. When the high speed stream has arrived the color changes to green.
2) Material from a CME is likely to impact Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.

Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. On 1510 kHz both Radio Rincón (Uruguay) and Radio Champaquí (Argentina) were audible at times. WDHP on 1620 and WWRU on 1660 had weak to fair signals during the half hour before local sunrise.

Active solar regions (Recent map)

Compare to the previous day's image.

Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SEC. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SEC or where SEC has observed no spots. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.

Active region Date numbered SEC
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10769 2005.05.28     S06W83     plage
10772 2005.05.31 2 1 S18W84 0060 DSO classification was HSX at midnight, area 0020
10773 2005.06.01 4 2 S14W44 0070 CSO classification was HAX at midnight, location: S14W41
10775 2005.06.04 17 18 N08W05 0330 DKC beta-gamma
location: N10W06
10776 2005.06.05 26 34 S06E07 0580 EKC beta-gamma
classification was EKI at midnight
10777 2005.06.10 4 1 N05E57 0030 BXO formerly region S557
classification was HRX at midnight, area 0010, location: N05E52
S555 2005.06.07     S03W40     plage
S556 2005.06.09     N05W08     plage
Total spot count: 53 56  
SSN: 103 106  

Monthly solar cycle data

Month Average solar
flux at Earth
International sunspot number Smoothed sunspot number
2000.04 184.2 125.5 120.8
cycle 23 sunspot max.
2000.07 202.3 170.1 119.8
2001.12 235.1 132.2 114.6 (-0.9)
2004.04 101.2 39.3 45.5 (-1.6)
2004.05 99.8 41.5 43.8 (-1.7)
2004.06 97.4 43.2 41.6 (-2.2)
2004.07 119.1 51.1 40.2 (-1.4)
2004.08 109.6 40.9 39.2 (-1.0)
2004.09 103.1 27.7 37.5 (-1.7)
2004.10 105.9 48.0 35.9 (-1.6)
2004.11 113.2 43.5 35.3 (-0.6)
2004.12 94.5 17.9 (34.8 predicted, -0.5)
2005.01 102.2 31.3 (32.8 predicted, -2.0)
2005.02 97.2 29.1 (30.4 predicted, -2.4)
2005.03 89.9 24.8 (28.8 predicted, -1.6)
2005.04 86.0 24.4 (26.9 predicted, -1.9)
2005.05 99.3 42.6 (24.3 predicted, -2.6)
2005.06 104.8 (1) 28.5 (2) (22.8 predicted, -1.5)

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC) sunspot number. The official international sunspot number is typically 30-50% less.

This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.


[DX-Listeners' Club]